Electro-active lenses generally include a liquid optical material (e.g., liquid crystal) encapsulated or contained by one or more solid, transparent optical materials. Conventional methods and structures for containing the liquid optical material often result in a visible seal ring on the lens indicating the positioning of the liquid optical material. These visible seal rings are cosmetically undesirable to consumers.
In conventional liquid crystal displays (LCDs), sealing features can typically be hidden behind an opaque frame or bezel. Such structures, however, are not viable for ophthalmic lenses and spectacle lenses in particular.
To date, methods and structures designed to reduce the visibility of any liquid optical material seal in an ophthalmic lens often compromise the structural integrity of the lens. As such, conventional methods for processing such lenses (e.g., conventional methods for cutting and edging a lens) can cause containment of the liquid optical material to be disturbed and can also disrupt the ability to alter the refractive index of the liquid optical material electronically. Consequently, many prior art electro-active lenses are not commercially viable products.
To address some of the foregoing problems, the inventors previously disclosed methods for manufacturing an electro-active semi-finished lens product, such as in U.S. Pat. Pub. No. 2009/0256977, incorporated herein by reference. Such methods may include the deposition of transparent, thin conductive films and electrodes onto ophthalmic quality substrates to enable the activation of the electro-active optic contained within the semi-finished lens blank.
Exploded views of the thin film coatings which may be used to produce an electro-active semi-finished lens blank (EASFB) are shown in FIGS. 1 and 2. In those examples, further details of which are discussed below, the electrodes are in physical contact with the thin conductive layers (in this case Indium Tin Oxide, ITO) and may be deposited/applied either immediately before (FIG. 1), or immediately after (FIG. 2), the ITO is deposited/applied.
Previous efforts, such as mentioned above, have included masking the deposition of ITO over a finite region of the substrate opposite of the electrodes to reduce the risk of electrical shorting. An example of this is shown in FIG. 3. While masking the deposition of ITO may achieve the desired goal of reducing electrical shorting, the inventors have found that it has a drawback in that the non-uniformity of the coatings may be highly visible in a finished lens, especially one that has been AR coated. This non-uniform appearance of the lens will be unacceptable in a commercially product.